Multiple Wireless Networks Management

ABSTRACT

A multiple wireless networks structure comprising a plurality of beacon groups each comprising one or more devices communicating via an associated wireless network utilising a superframe structure; wherein each device of each beacon group allocates a local control period and one or more neighbor control periods in each superframe; wherein the neighbor control periods in each beacon group cover all one or more control periods of other beacon groups detected by one or more of the devices in said each beacon group to an extent as said control periods do not overlap with the local control period in said each beacon group.

FIELD OF INVENTION

The present invention relates broadly to a multiple wireless networksstructure, a method of managing a wireless multiple networks structure,and to a method of announcing the presence of a first beacon group to asecond beacon group.

BACKGROUND

In view of problems of the Wireless Personal Area Network (WPAN) MACprotocol of the IEEE standard 802.15.3, which is based on acentralized-control protocol, the Multi-Band OFDM (Orthogonal FrequencyDivision Multiplexing) Alliance (MBOA) group started its MBOA MACsubgroup. To address the problems of the IEEE 802.15.3 MAC such asSimultaneous Operating Piconet and Mobility issues, the MBOA MAC isbased on a distributed protocol rather than a centralized-controlledone. In order for every device to be able to form a network by itself,each device is required to beacon in a distributed fashion. The MBOA MACv0.5 defines the superframe of a device to be of 65536 μs. Thesuperframe is to be composed of 256 Media Access Slots (MASs) where eachMAS length is 256 μs. The first 8 MASs of a superframe, relative to anindividual group, are defined as a Beacon Period (BP) and aresub-divided into 24 Beacon Slots (BSs). The rest of the MASs in thesuperframe are used for data transfer, employing either EDCA (EnhancedDistributed Channel Access) (data contention method) or DRP (DistributedReservation Protocol) (data reservation method). The superframe 100 ofMBOA MAC is illustrated in FIG. 1.

Devices powering up first scan the medium for any existing network bylistening to beacon frames. If beacon frames are heard, each deviceattempts to broadcast their beacon in a randomly selected vacant BS.Devices receive the BS occupancy information via the beacon ofneighboring devices through the Beacon Period Occupancy InformationElement (BPOIE) transmitted together within every beacon.

In order to support more than 24 devices in different groups operatingsimultaneously, the MBOA MAC protocol allows devices to create andbroadcast their beacons in new BPs different from existing ones. Thismeans that in a superframe of a device, there can be multiple BPs usedby other neighboring devices. Another reason for having multiple BPs isnetwork merging between 2 or more Beacon Groups (BG), illustrated inFIG. 2. A BG is formed by 1 or more devices beaconing in the same BP.

The MBOA MAC protocol allows devices within the same BG to communicate.Since each device listens in the BP of the local cluster around eachdevice, data reservation announcements in the BG can be heard via beaconframes. However, for a device to communicate with another device inanother BG, the communicating device is required to beacon in the targetdevice's BP as well.

When a neighboring BG is detected, first the local BG informs thedevices in the local BG of the presence of the neighboring BG via thebeacon of the local BG. In addition, the local BG attempts to inform theneighboring BG if the local BG determines that the local BG is notprotected in the same way as the neighboring BG. To do so, the local BGtransmits a beacon frame in the BP of the neighboring BG for a number ofconsecutive superframes. The BS the local device uses is chosen atrandom from the list of available vacant slots.

In mandating a device to beacon in a neighboring BP so that datacommunication is enabled across BGs, unnecessary beaconing is imposed onthe beaconing device.

To protect the neighboring BG, a device sends out a reservation requestto block devices in the local BG from using the BP of the neighboringBG. In the case of multiple neighboring BGs having one or more BPsoverlapping, a device has to send this reservation multiple times.

When making a neighboring BG announcement, a device uses a BS of theneighboring BG's BP. The neighboring BG's BP may be running low inavailable BSs and this might cause new devices not being able to jointhe neighboring BG. In addition, if there are no more BSs available,that neighboring BG cannot be informed of the presence of the local BG.

In addition, if multiple BGs make announcement beaconing to the sameneighboring BG, announcement beacon frames may colloid. This makesannouncement beaconing unreliable.

SUMMARY

In accordance with a first aspect of the present invention there isprovided a multiple wireless networks structure comprising a pluralityof beacon groups each comprising one or more devices communicating viaan associated wireless network utilising a superframe structure; whereineach device of each beacon group allocates a local control period andone or more neighbor control periods in each superframe; wherein theneighbor control periods in each beacon group cover all one or morecontrol periods of other beacon groups detected by one or more of thedevices in said each beacon group to an extent as said control periodsdo not overlap with the local control period in said each beacon group.

The local control period of each beacon group may comprise a beaconperiod for beacon announcements in said each beacon group, and anon-reservation period for communications other than said beaconannouncements in said each beacon group.

The local control period of each beacon group may further comprise oneor more neighbor non-reservation periods covering respectivenon-reservation periods of one or more other beacon groups detected byone or more devices in said each beacon group to an extent as saidrespective non-reservation periods do overlap with the beacon period insaid each beacon group.

The superframes of the respective beacon groups may further comprise oneor more data periods outside the local control period and the neighborcontrol periods, for data communications.

In accordance with a second aspect of the present invention there isprovided a method of managing a wireless multiple networks structurecomprising a plurality of beacon groups each comprising one or moredevices communicating via an associated wireless network utilising asuperframe structure, the method comprising allocating, for each beacongroup, a local control period and one or more neighbor control periodsin each superframe; wherein the neighbor control periods in each beacongroup cover all one or more control periods of other beacon groupsdetected by one or more of the devices in said each beacon group to anextent as said control periods do not overlap with the local controlperiod in said each beacon group.

The local control period of each beacon group may comprise a beaconperiod for beacon announcements in said each beacon group, and anon-reservation period for communications other than said beaconannouncements in said each beacon group.

The local control period of each beacon group may further comprise oneor more neighbor non-reservation periods covering respectivenon-reservation periods of one or more other beacon groups detected byone or more devices in said each beacon group to an extent as saidrespective non-reservation periods do overlap with the beacon period insaid each beacon group.

The superframes of the respective beacon groups may further comprise oneor more data periods outside the local control period and the neighborcontrol periods, for data communications.

In accordance with a third aspect of the present invention there isprovided a method of announcing the presence of a first beacon group toa second beacon group, each beacon group comprising one or more devicescommunicating via an associated wireless network utilising a superframestructure, the method comprising each device of the first grouplistening for a beacon broadcast from a device of the second beacongroup outside a control period of the superframe structure in the firstbeacon group; detecting of said beacon broadcast by at least one of thedevices of the first group; said at least one device of the first groupincluding in a beacon broadcast to the other devices in the first groupdata identifying a control period of the second beacon group; andallocating, in the first beacon group, a neighbor control period in eachsuperframe covering said control period of the second beacon grouprelative to the superframe structure of the first beacon group.

The method may further comprise said at least one device of the firstbeacon group listening during said neighbor control period for beaconbroadcasts from one or more devices of the second group; and determiningwhether any such beacon broadcast comprises data identifying the controlperiod, of the first beacon group.

The method may further comprise said at least one of the devices of thefirst beacon group making an announcement during said neighbor controlperiod.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be better understood and readilyapparent to one of ordinary skill in the art from the following writtendescription, by way of example only, and in conjunction with thedrawings, in which:

FIG. 1 shows the timing structure of a prior art superframe of MBOA MACv0.5 draft specification.

FIG. 2 is a schematic drawing illustrating how multiple BPs in a priorart superframe can be caused by network merging of multiple BGs.

FIG. 3 shows the timing structure of a superframe according to anexample embodiment.

FIG. 4 shows the timing structure of a BP according to an exampleembodiment.

FIG. 5 illustrates the concept of LCP and NCP according to an exampleembodiment.

FIG. 6 shows the formation of an extended NCP from overlapped CPsaccording to an example embodiment.

FIG. 7 shows the case when a neighbor BG's CP overlaps the LCP accordingto an example embodiment.

FIG. 8 shows a schematic drawing of a device for use in multiplewireless networks management according to an example embodiment.

FIG. 9 shows a flowchart of a method of managing a wireless multiplenetworks structure comprising a plurality of beacon groups eachcomprising one or more devices communicating via an associated wirelessnetwork utilising a superframe structure, according to an embodiment ofthe present invention.

FIG. 10 shows a flowchart of a method of announcing the presence of afirst beacon group to a second beacon group, each beacon groupcomprising one or more devices communicating via an associated wirelessnetwork utilising a superframe structure, according to an embodiment ofthe present invention.

FIG. 11 shows a schematic drawing of a multiple wireless networksstructure according to an example embodiment.

DETAILED DESCRIPTION

In the example embodiment, a device only broadcasts a beacon frame oncein every superframe even if the device communicates with a device inanother BG. This can have the advantage of reducing power consumption aswell as reducing implementation complexity.

A Non-Reservation Period (NRP) in the example embodiment provides amechanism for neighboring BG announcement even in the case where theneighboring BG is full. This can solve the problem of the prior artwhere an announcement cannot be made when all BSs are used. During NRP,a contention medium access mechanism is used. In the case where multipleBGs attempt to make a BG announcement simultaneously, thecontention-based mechanism of the example embodiment can provide arobust method to prevent and resolve collisions.

Each device manages neighboring BG announcement using a Local ControlPeriod (LCP) and a Neighbor Control Period (NCP) concept in the exampleembodiment. In the case of multiple overlapped BGs, only a single NCP isrequired to describe the period that is not to be used for datacommunication. This reduces the overhead in sending multiple BPreservations in the prior art.

The LCP and NCP concepts in the example embodiment also help to improvethe spatial efficiency of the medium. In the case where a BG overlaps alocal BG, the overlapped portion of a Control Period (CP) can be used byboth BGs. The non-overlapped portion of the CP is treated as NCP.

The distributed beaconing method in the example embodiment performs thefollowing operations. Each device broadcasts a beacon frameperiodically. For each device, the timing structure is a superframe. Thesuperframe structure is defined as shown in FIG. 3 for the exampleembodiment. With reference to FIG. 3, the superframe 300 is divided intoa finite number of MASs, e.g. 302. The number of MASs may have typicalvalues of 64, 128, 256 or any integer number of slots. The MASs in thesuperframe 300 are divided into a CP 304 and a Data Period (DP) 306. Thenumber of MASs used for CP 304 and DP 306 can be predetermined in anyconfiguration provided that they add up to the total number of MASs inthe superframe 300. One example is to have CP 304 using 8 slots, DP 306using 248 slots, making the number of MASs in the superframe 300 to be256. The CP 304 is further divided into a BP 308 and a NRP 310. Again,period BP and NRP uses a pre-determined number of MASs. A superframe isuniquely identified by its Beacon Period Start Time (BPST).

The BP 308 itself is subdivided into BSs e.g. 312, as shown in FIG. 4.Each MAS e.g. 302 in the BP 308 may be divided into several BSs. In thecase of FIG. 4, 1 MAS is divided into 3 BSs. In other variations of theimplementation, 1 MAS may correspond to 1 BS, or may be divided into 2,4, 5 or any number of BSs.

In this the example embodiment, each device broadcasts a beacon frameonce during every superframe. Each device broadcasts its beacon framesin a BS.

Before data communication can take place, a device must either create anew BG or join an existing BG. Once a device starts broadcasting abeacon frame on one particular BS, the device shall continue to use thatBS unless a collision is detected. If a collision is detected, acollision resolution protocol such as the one in the prior art of MBOAMAC specification can be used in the example embodiment. Othercollisions resolution protocols may be used in different embodiments.

In addition to the devices in the same BG, there may be other devices inthe radio vicinity that use different BPs of different BPSTs. In thatcase, two or more BGs may coexist. As shown in FIG. 5, relative to BG-1,the CP 502 used by the local BG is defined as LCP 500. The CP 504 usedby the neighboring BG-2 is defined as NCP 506. The DP that is supposedto be shared by any devices regardless of BG are the same, and not shownin FIG. 5.

Similarly, relative to BG-2, the CP 504 used by the local BG is definedas LCP 508, and the CP 502 used by the neighboring BG-1 is define as NCP510. Again, the DP that is supposed to be shared by any devicesregardless of BG are the same.

The CPs of the neighboring. BGs may overlap, as shown in FIG. 6. In thatcase, relative to BG-1, the CPs. 600, 602, 604 of the overlapped BGswill be combined to form a NCP 606 that extends across all consecutiveMASs, that are used by the neighboring BGs.

The CP 700 of a neighboring. BG-2 may also overlap with the LCP 702 of aBG-1, as shown in FIG. 7. In that case, the non-overlapped portion ofthe CP 700 of the neighboring BG-2 will form a NCP 704 relative to BG-1.In the example embodiment, devices also take note of an overlapping BG'sNRP. If e.g. the NRP 706 of BG-1 overlaps with BP 708 of BG-2, the BSsmust be marked as Neighbor NRP (NNRP) 710 relative to BG-2 and not beused by any device in the BG-2 for beaconing. If there are alreadydevices beaconing in those slots, collision resolution protocol shall beinitiated to prevent those devices from beaconing in those NNRP 710slots.

In the example embodiment, each device, e.g. of BG-1, beacons during theBP e.g. 712 in the devices LCP 702, and in the device's respective BS.In other BSs, each device listens for other device's beacon frame. TheNRP 706 in the. LCP 702 is used to communicate network related commandsor announcements. Alternatively, it can be used to send shortasynchronous data. Within the NRP 706, a priority-based contentionmedium access mechanism is used. Devices sending commands orannouncement content may have a higher priority compared to a devicewishing to send data. This can ensure the medium access goes first toimportant command and announcement use. In addition to beaconing andlistening during LCP 702, each device in BG-1 is also required to listenoutside the LCP. 702 for any beacon broadcast from neighboring BGs.

When a listing device detects a neighboring BG, that listing devicefirst protects the neighboring BG's CP from being used by any device inthe local BG of the listing device for data communications. To do so,the listing device includes in their beacon, a list of NCPs,corresponding to the CPs of the neighboring BG detected. The format todescribe a NCP can be a “start MAS, end MAS”, “start MAS, length ofNCP”, or different combinations or formats in different embodiments.

After protecting. a neighboring BG's CP, the listing device also checkswhether the local BG's CP is itself being protected by the neighboringBG. This can be checked from listening to beacon broadcasts during theneighboring BG's BPs, i.e. in the NCPs relative to the listening device.If there are no devices in the neighboring BG protecting the local BG,the listing device announces its BG's presence. This announcement may bedone by contenting in the neighboring BG's NRP with the highestpriority, to send the announcement frame. A device that hears aneighboring BG announcement frame during the NRP shall include theneighbour BG information in its beacon in the following superframe. Thiscan ensure that all devices in the BG are informed of the announcement.After sending the announcement frame, the device shall listen into thenext superframe of the neighboring BG to verify if any device in theneighboring BG has heard the announcement. The device then includes anysuch neighboring device in the next beacon announcement. If noneighboring devices are heard protecting the local BG, the listingdevice performs the announcement procedure again until at least oneneighboring device is heard protecting the listing device's local BG'sCP.

With reference to FIG. 8, there is illustrated an electronic device 801for use in an example embodiment of the present invention. The device801 illustrated is a wireless communication device that consists of awireless physical layer PHY 802 to enable wireless communication; aMedium Access Control (MAC) layer 804 to control how the wireless mediumis to be shared and used. A method according to an embodiment of thepresent invention is applied in the MAC layer 804; a Device driver 806to use the services provided by the MAC layer 804, a chipset (not shown)in the wireless PHY layer 802; an application software 808 that uses thedevice driver 806 to control the communication, and an interface 810 andscreen hardware 812 to deliver to a user the required user-application.The Interface 810 also enables user input, and the screen 812 displaysapplication-specific data to the user.

FIG. 9 shows a flowchart of a method of managing a wireless multiplenetworks structure comprising a plurality of beacon groups eachcomprising one or more devices communicating via an associated wirelessnetwork utilising a superframe structure, according to an embodiment ofthe present invention. At step 900, a local control period is allocatedfor each beacon group in each superframe. At step 902, one or moreneighbor control periods are allocated for each beacon group in eachsuperframe. The neighbor control periods in each beacon group cover allone or more control periods of other beacon groups detected by one ormore of the devices in said each beacon group to an extent as saidcontrol periods do not overlap with the local control period in saideach beacon group.

FIG. 10 shows a flowchart of a method of announcing the presence of afirst beacon group to a second beacon group, each beacon groupcomprising one or more devices communicating via an associated wirelessnetwork utilising a superframe structure, according to an embodiment ofthe present invention. At step 1000, each device of the first grouplistens for a beacon broadcast from a device of the second beacon groupoutside a control period of the superframe structure in the first beacongroup. At step 1002, said beacon broadcast is detected of by at leastone of the devices of the first group. At step 1004, said at least onedevice of the first group includes in a beacon broadcast to the otherdevices in the first group data identifying a control period of thesecond beacon group. At step 1006, a neighbor control period isallocated in the first beacon group in each superframe covering saidcontrol period of the second beacon group relative to the superframestructure of the first beacon group.

FIG. 11 shows a schematic drawings of a multiple wireless networksstructure 1100 comprising according to an embodiment of the presentinvention. The multiple wireless networks structure 1100 comprises aplurality of beacon groups e.g. 1102, 1104, each comprising one or moredevices e.g. 1106 communicating via an associated wireless networkutilising a superframe structure. Each device e.g. 1106 of each beacongroup e.g. 1102 allocates a local control period and one, or moreneighbor control periods in each superframe. The neighbor controlperiods in each beacon group e.g. 1102 cover all one or more controlperiods of other beacon groups e.g. 1104 detected by one or more of thedevices 1106 in each beacon group e.g. 1102 to an extent as the controlperiods do not overlap with the local control period in each beacongroup e.g. 1102.

The embodiments described can provide a method to simplify themanagement of independent BGs, particularly in cases where multiple BGs'BP overlap. This embodiments described also seek to provide a method toachieve neighbour announcements without sacrificing any beacon slots ineither local or neighbor BP.

It will be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

1-11. (canceled)
 12. A multiple wireless networks structure comprising:a plurality of beacon groups each comprising one or more devicescommunicating via an associated wireless network utilising a superframestructure; wherein each device of each beacon group allocates a localcontrol period and one or more neighbor control periods in eachsuperframe; wherein the neighbor control periods in each beacon groupcover all one or more control periods of other beacon groups detected byone or more of the devices in said each beacon group to an extent assaid control periods do not overlap with the local control period insaid each beacon group.
 13. The multiple networks structure as claimedin claim 12, wherein the superframes of the respective beacon groupsfurther comprise one or more data periods outside the local controlperiod and the neighbor control periods, for data communications. 14.The multiple networks structure as claimed in claim 12, wherein thelocal control period of each beacon group comprises a beacon period forbeacon announcements in said each beacon group, and a non-reservationperiod for communications other than said beacon announcements in saideach beacon group.
 15. The multiple networks structure as claimed inclaim 14, wherein the superframes of the respective beacon groupsfurther comprise one or more data periods outside the local controlperiod and the neighbor control periods, for data communications. 16.The multiple networks structure as claimed in claim 14, wherein thelocal control period of each beacon group further comprises one or moreneighbor non-reservation periods covering respective non-reservationperiods of one or more other beacon groups detected by one or moredevices in said each beacon group to an extent as said respectivenon-reservation periods do overlap with the beacon period in said eachbeacon group.
 17. The multiple networks structure as claimed in claim14, wherein the superframes of the respective beacon groups furthercomprise one or more data periods outside the local control period andthe neighbor control periods, for data communications.
 18. A method ofmanaging a wireless multiple networks structure comprising a pluralityof beacon groups each comprising one or more devices communicating viaan associated wireless network utilising a superframe structure, themethod comprising: allocating, for each beacon group, a local controlperiod and one or more neighbor control periods in each superframe;wherein the neighbor control periods in each beacon group cover all oneor more control periods of other beacon groups detected by one or moreof the devices in said each beacon group to an extent as said controlperiods do not overlap with the local control period in said each beacongroup.
 19. The method as claimed in claim 18, wherein the superframes ofthe respective beacon groups further comprise one or more data periodsoutside the local control period and the neighbor control periods, fordata communications.
 20. The method as claimed in claim 18, wherein thelocal control period of each beacon group comprises a beacon period forbeacon announcements in said each beacon group, and a non-reservationperiod for communications other than said beacon announcements in saideach beacon group.
 21. The method as claimed in claim 20, wherein thesuperframes of the respective beacon groups further comprise one or moredata periods outside the local control period and the neighbor controlperiods, for data communications.
 22. The method as claimed in claim 20,wherein the local control period of each beacon group further comprisesone or more neighbor non-reservation periods covering respectivenon-reservation periods of one or more other beacon groups detected byone or more devices in said each beacon group to an extent as saidrespective non-reservation periods do overlap with the beacon period insaid each beacon group.
 23. The method as claimed in claim 22, whereinthe superframes of the respective beacon groups further comprise one ormore data periods outside the local control period and the neighborcontrol periods, for data communications.
 24. A method of announcing thepresence of a first beacon group to a second beacon group, each beacongroup comprising one or more devices communicating via an associatedwireless network utilising a superframe structure, the methodcomprising: each device of the first group listening for a beaconbroadcast from a device of the second beacon group outside a controlperiod of the superframe structure in the first beacon group; detectingof said beacon broadcast by at least one of the devices of the firstgroup; said at least one device of the first group including in a beaconbroadcast to the other devices in the first group data identifying acontrol period of the second beacon group; and allocating, in the firstbeacon group, a neighbor control period in each superframe covering saidcontrol period of the second beacon group relative to the superframestructure of the first beacon group.
 25. The method as claimed in claim24, further comprising said at least one device of the first beacongroup listening during said neighbor control period for beaconbroadcasts from one or more devices of the second group; and determiningwhether any such beacon broadcast comprises data identifying the controlperiod of the first beacon group.
 26. The method as claimed in claim 25,further comprising said at least one of the devices of the first beacongroup making an announcement during said neighbor control period.